Changing tooltip for menu entries which use the same operator
Using a dynamic operator enum property
Add a custom property &quot;prop&quot; to the scene to show dynamic behaviour.  Once added will add a new item to menu.
import bpy
#populate itemslist
def items_list(self, context):
    items = [
        (&quot;RED&quot;, &quot;Red&quot;, &quot;This will add RED&quot;,  'OUTLINER_OB_ARMATURE', 1),
        (&quot;GREEN&quot;, &quot;Green&quot;, &quot;This will add GREEN&quot;,  'OUTLINER_OB_ARMATURE', 2),
        (&quot;BLUE&quot;, &quot;Blue&quot;, &quot;This will add BLUE&quot;,  'X', 4),
        (&quot;YELLOW&quot;, &quot;Yellow&quot;, &quot;This will add YELLOW&quot;,  'BLENDER', 8),
        ]
    # test dynamic by adding custom prop &quot;prop&quot; to scene
    if &quot;prop&quot; in context.scene.keys():
        items.append(('BLACK', &quot;Black&quot;, &quot;This will add BLACK&quot;, 'BLANK', 16))
    return items


def draw_enum(self, context):
    self.layout.operator_context = 'INVOKE_REGION_WIN'
    self.layout.operator_menu_enum(&quot;object.simple_operator&quot;, &quot;type&quot;, text=&quot;My Menu&quot;)
    
bpy.types.INFO_MT_add.append(draw_enum)

class SimpleOperator(bpy.types.Operator):
    bl_idname = &quot;object.simple_operator&quot;
    bl_label = &quot;Add Avastar...&quot;
    bl_description= &quot;Avastar&quot;
    #bl_options = {'REGISTER', 'PRESET', 'UNDO'}
    #dynamic enum property
    type = bpy.props.EnumProperty(items=items_list)
    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        print(&quot;run with &quot;, self.type)
        return {'FINISHED'}

def register():
    bpy.utils.register_class(SimpleOperator)

def unregister():
    bpy.utils.unregister_class(SimpleOperator)

if __name__ == &quot;__main__&quot;:
    register()


PS: from your screenshot it looks like you are using presets, check out Python add drop down menu that stores data  The preset code is in 2.77/scripts/startup/bl_operators/presets.py